Simplify the following expression: $\dfrac{12r^4}{2r^4}$ You can assume $r \neq 0$.
Explanation: $ \dfrac{12r^4}{2r^4} = \dfrac{12}{2} \cdot \dfrac{r^4}{r^4} $ To simplify $\frac{12}{2}$ , find the greatest common factor (GCD) of $12$ and $2$ $12 = 2 \cdot 2 \cdot 3$ $2 = 2$ $ \mbox{GCD}(12, 2) = 2 $ $ \dfrac{12}{2} \cdot \dfrac{r^4}{r^4} = \dfrac{2 \cdot 6}{2 \cdot 1} \cdot \dfrac{r^4}{r^4} $ $\phantom{ \dfrac{12}{2} \cdot \dfrac{4}{4}} = 6 \cdot \dfrac{r^4}{r^4} $ $ \dfrac{r^4}{r^4} = \dfrac{r \cdot r \cdot r \cdot r}{r \cdot r \cdot r \cdot r} = 1 $ $ 6 \cdot 1 = 6 $